import { Bytes, BytesLike, underlying } from "./bytes";

export type IOList = number | BytesLike | IOList[] | false | CountedIOList;

class CountedIOList {
    value: IOList;
    length: number;

    constructor(i: IOList) {
        this.value = i;
        this.length = iolistLength(i);
    }
}

export function pushByte(i: IOList, b: number): IOList {
    if (Array.isArray(i)) {
        i.push(b);
        return i;
    } else {
        return [i, b];
    }
}

export function append(i: IOList, j: IOList): IOList {
    if (i === false) return j;
    if (j === false) return i;
    return [i, j];
}

export function iolistLength(i: IOList, acc = 0): number {
    if (typeof(i) === 'number') return acc + 1;
    if (i === false) return acc;
    if (Array.isArray(i)) return i.reduce<number>((acc, j) => iolistLength(j, acc), acc);
    if (i instanceof CountedIOList) return acc + i.length;
    return acc + i.length;
}

export function countIOList(i: IOList): CountedIOList {
    if (i instanceof CountedIOList) return i;
    return new CountedIOList(i);
}

export function ioListBytes(i: IOList): Bytes {
    if (i instanceof Bytes) return i;
    const buffer = new Bytes(iolistLength(i));

    function fill(i: IOList, offset: number): number {
        while (i instanceof CountedIOList) i = i.value;
        if (typeof(i) === 'number') {
            buffer._view[offset] = i;
            return offset + 1;
        }
        if (i === false) {
            return offset;
        }
        if (Array.isArray(i)) {
            i.forEach(j => offset = fill(j, offset));
            return offset;
        }
        const bs = underlying(i);
        buffer._view.set(bs, offset);
        return offset + bs.length;
    }

    fill(i, 0);
    return buffer;
}